A typical RF system includes a relatively powerful transmitter and a sensitive receiver both connected to the same antenna. Occasionally, multiple unrelated antenna systems may be within range of each other, and may be operating within the same frequency spectrum. Accordingly, interference may result from various different signals being produced within the same band.
However, signals can be modulated by applying a code to a signal in its digital form such that certain bits of the digital signal are switched from 0 to 1 or from 1 to 0. That is, a binary signal can be modulated by a binary code, with the modulated digital signal thereafter being converted to an analog signal for transmission. For example, spread spectrum orthogonal coding has been done at baseband analog and baseband digital, but has not yet been attempted at RF, and has not been attempted after the amplifier change on a transmit channel, as the module should be able to handle very high power corresponding to a high-power signal.
Thus, this application describes an antenna system that provides spread spectrum orthogonal coding at the RF level.